Apparatus for testing the foaming characteristics of liquids



H. G. SMITH July 3l, 1945.

APPARATUS FOR TESTING THE FOAMING CHARACTERISTICS OF LIQUIDS Filed Aug. 25, 1944 @Armi/J Patented July 31, 1.945

APPARATUS FOB TESTING THE FOAMING CHARACTERISTICS 0l" LIQUIDS Herschel G. Smith, Wallingford, Ps., assignor to Gulf Oil Corporation, Pittsburgh, Pa., a corporation of Pennsylvania Application August 25,1944, Serial No. 551,230

lClaim.

l invention relates to an improved apparatus for testing the foaming characteristics of liquids, particularly oil samples to which various l anti-foam agents have been added.

The purpose of such tests is to determine the s Izlcacyof various agents for suppressing or in hibiting trothing and foaming of lubricating oil such as occurs, for example, in the night of aircraft. Foaming, if excessive, starves the engine of sumclent oil for lubrication and rapidly leads to l0 mechanical failure. Hence, research in this eld contemplates testing oil with suitable agents added .to it in diiiering amounts', by blowing or diilusing air or other gaseous fluids through the test sample under controlled conditionaas one l5 such testing procedure. Y

It is important that two conditions be maintained: First, since additions of the anti-foam agent are relatively small and any adhering mixture from oneI sample, it carried over to another, so

would destroy the accuracy. of tests in the succeedingone. the porous diffusing surface must be scnxpulously clean at the beginning of each test. Second, the amusing surface should approximate the diameter-of the receptacle for the sampleso 86 that air diffusing into the body of oil forms minute bubbles which are substantially homogeneously distributed. The apparatus of the present invention fulfills these requirements, for it provides a diffusing diaphragm which is intended to be dis- 30 carded after a single use, so that laborious cleaning and possible contamination of other samples are avoided. Also, the diaphragm is o! such diameter that the air bubbles are released uniformly into practically all of the overlying oil clumm 435,

In a general sense the arts describe many methods of producing gas foams in oil. Static methods are those in which the measurements of the foam are made after the' foam has been produced often with no reference to the manner of production of 40,

theoil aero foam. In dynamic methods, on the other hand. measurements-are made while. foam is beingiormed, usually'hy a current of gas being distributed and passed through the liquid. A

static method may comprise'the step of forming 45 the foam by an indicated procedure. then observing the rate at which the Aliquid drains or collects from the foam, the observations being started after cessation o! foam formation. In dynamic methods the question of drainage from the foam 60 is focused 'more on the position of the topmost 'nie present invention is concerned primarily. with an improved dynamic method of .forming oil gasicamwherelntheeilects'thstaresctually U Cl. l'I3-43) Ol course it is to be expectedl that this kdynamic.

type of foam formation would undoubtedly involve some of the principles of static methods, for

it is impossible to prevent draining of some liquid from the foam. l

In the arts several methods have been devised to accomplish the desired effect. method is to use some form of fritted or sintered glassware air disperser, which contains minute ports through whichgas may be passed as fine bubbles into the liquid. This type of apparatus has many disadvantages; the holes become clogged up and difilcult toclean, especially it the oil through which gas is being distributed contains a colloidal suspension of some sort. Moreover, the type of fritted glassware on the market today is usually of uneven porosity, `the holes varying in size from 5-206 microns pore diameter so that it is diflipult to control the rate at which gas is distributed throughout the oil medium. s

Similar to the above-mentioned apparatus are a number of porous stone types of distributors which have been used for distributing gas through the oil medium. These porous stones likewise have the disadvantages mentioned above for the fritted orsiniered glass type of gas device apparatus. l

Approaching the4 problem from a practical standpoint, applicant has devisedan apparatus for accomplishing thedistrlbution of gas through `an oil medium so that the above-mentioned distage of not clogging up overa period of time,

because the individual lter paper disk may be replaced after each use with an inexpensive new one of the same porosity. The illter papers will withstand enough pressure so as to allow air to now throw-h the mr paper and be distributed ineven bubbles in the lower portion of the oil medium. slowly rising through the oil medium to the surface where the bubbles accumulate for a period ottime. The porous material is held in the lower portion of the apparatus between two peper gaskets by clamping or screwing a small The 'usual' ring in me battomsonmner. ss is more :u uy

apparent by reference to the accompanying. drawing and following detailed description. u

Inthedrawing: Fig. lisaview partly in section andpartly in elevation showing "the sezating device lowered into the cylinder;

Fig. 2 is a plan view of the illter holder por-v tion of the aerating device, a portion of the air tube being shown in section, a tool for tightening the clamping ring being shown applied to the holder; and

isfound superior teeny other device so far known for accurate determination of foaming characteristics of a liquid under standard conditions, as

Vwellas for effective aeration, oxidation, or other l actions of interest between gases and liquids For testing Aof products for commercial purposes two main types of tests forthe foaming characteristics of -an oil have been employed. One consists of application of high speed beaters 'tu' paddles for measuring the probable mechani- -ca1 development of foam in operation; merely from ythe air or other gas drawn or whipped into the liquid during the operation; as, for example, the determination of the tendency of an oil lto build up foam while in operation in agear case. Another test of interest involves the determination of foaming characteristics of an oil or' other f which is connecteda roundtu'be to supply air or other gas admitted to the holder, with s.l clampedin diaphragm held tightly by suitable gaskets and threaded ring, which may be tightened by a small spanner wrench, in horizontal -position relative to the dat disk holder.

For aeration of non-aqueous liquids, such as -petroleum oils, for study oflfoaming characteristics, diaphragm; of standard final filter papers may beused, ysuch ,as Whaiznan No. 40 illter paper, cut to desired size by a punch type cutter of the same general design employed for cutting washers, or shot gun wads. Disks and washers of other materials can also be cut in the saine manner from blottingpaper, fine linen, or other suitable materials', where needed. In the case oi the use of this same type apparatus for aqueousy solutions, or mixtures of water and oil, or the like, where the illter paper itself will soak up the 'reactions or interactions. The present apparatus water and wiu et times be broken by the modl erate air ,or gas pressure employed.' due to softening` of the bers, fine linen disks may be used for some work, while s combination of selected 'very fine filter paper covered bylinen disk for additional strength for any desired line division of gas, V

or air may also be employed where water is present. 'Ihe regular type of differential capillary tubeair meter delivering' about.10 liters per hour l may be employed for the test, preferably standardized satisfactorily for multiple units, although axfy suitable air meter cahbe used, Aas a matter of convenience. A pressure oi around 100 mm.

mercuryhas proved satisfactory for use with present equipment for a preferred vtype of paper diaphragm for securing the ne bubbles. Thus thereis proveded ilexibility in the operationand selection of matexialstor this equipment. for carryingk'out any operation desired along these lines in the way of aeratiov or reaction of gas with liqliquid when airis passed into it as extremely fine bubbles, with resultant minimum of agitation tending to break down fragile bubbles, so that the:

foamwilltend to develop with "quietfincreasag, with little or no mechanicalagitatlonsfrom stir ring or agitating eii'ect from bubbles. The ideal condition for auch development isto pass the air into the liquid'in suche, line state of division as to fpmdueealgnduai bund-up of foam in quietly rising stage. as otherwise the stirring .eifect from'largelbubbles mixing with uids .for the y of determining foaming characteristics of a quid, as well as foracc'elerated reaction tests.

Referring to the drawing, A denotes generally the lter holder which is adapted to be lowered' into a graduated cylinder B preferabiy'of glass or like transparent material. 'I'he filter holder is provided with an air or gas supply tube C which is detachably secured to the holder and is adapted to supply air or gas imderpressure beneath the removable filter paper disk or disks carried by the holder. The'vertical supply pipe C may be con,-

. nected through any suitable means to a source of small bubbles willtend to approach the me-, chanical whipper test typabut with erratic intermediatc results. The last-mentioned type of test is of practical interest as indicating what will happen. for example, in a tank of liquid fromand to which the liquid ls cli'ulatcd, with the returning liquidbearing air or other-gas in very une state o'f subdivision, with little or no agitation inthe tank. In practice. most actual condixtions of operation encountered lie somewhere between the two effects, that of run mechanical o'n stream, so that by using both tests we flnethelimitsinbothdirecticns. t*

The present invention pertains to the purely mechanical development. desisn. and use of4 a special non-agitating aerating device which produces reliable eiects from the to the exposed surface of air or other gas' in any deslred extremely line state of subdivision of bubbles. To accomplish this eil'ect I have designed an improved type of aerating apparatus compriscan de"- agitation and that of absolutely quiet aeration pump (not shown).

MDL?. as, for example, through horizontal pipe D, gas, pressure regulator E and supply pipe F, which receives air or gas from a suitable source of pressure, as, for example. a pressure tank or The graduated cylinder B may be lled with liquid G to a suitable level H, and above the liquid level bubbles will rise when air isfsupplied through the pipe C to a level K which may be measured upon the scale M carried by thebeaker or container B.

The illfer holder as shown comprises a dishlike base member Il whichmay be composed of any suitable material, as for example, copper, brass or other metal, or oi' synthetic material, such as plastic resins or the like. The base member isprovided with an annular shoulder Il midway between'the bottom and 'top of the base member upon which one or more gaskets I2 of paper fibre or other suitable material may be placed. -Over the gasket Il one or more paper disks I3 of porous material, such as iilter paper, may be located. Another gasket l2 may be placed ing a metallic or other holder of ilat disk typebto 7.5 over the filter paperdisk. The nlter paper and above the shoulder II.

gaskets areclamped in place by theuse of a suitthreaded portion I4 of the base member located The clamping ring I5 is suitably screw-threaded at I6 to correspond with the threads Il in the base member. In order to tightly clamp the ring a plurality of spaced pins I1 Ymay be provided which are adapted to cooper- 'ate with a suitable tool or wrench yIl having a slot therein adapted to engage with one of the pins while the rear of the tool engages a pinon the l able clamping ring which is secured into a screwopposite side of the ring while the handle por-` tion'oi the tool extends beyond the holder and may be graspedJby the operator.

Below the shoulder member II of the base portion is a horizontal opening or passage I9 which communicates with vertical passage which is suitably screw-threaded to receive correspondingly threaded lower portion 2l ofthe air pipe C.

The pipe C may be provided with a suitable connecting nipple 22 at the upper portion thereof,

by which the vertical pipe is connected to the lateral pipe D. y

. Operation While it will be obvious that the foam testing operation may be carried out under varying conditions, a particular test under specified conditions will now be described:

The test was conducted in a room having a temperature of about 77 F. The temperature of the v room should not be lower than about '70 F. A circle of Whatman No. 40 illter paper or its equivalent' 1H inches in diameter was inserted between two paper gaskets I2, `I2 having an inner diameter of 1% inches and an outer diameter of 1H inches. The clamping-ring I5 was screwed into place and tightened `by means of the wrench I8. The assembled aerator was then inserted into a 100G-cc. cylinder so that the bottom of the aerating device rested in the bottom of the cylin.

der. A portion ot the sample of oil to be tested,

previously adjusted to approximately 77 F., was poured into the cylinder until the 250-cc. mark was reached, allowing 20 ccs. as the approximate displacement volume of the aerator in actual operation. The aerating device was then connected to the air line running from an air ow gauge.

-The air supply was then turned on and the pressure adjusted so that the air rate of ilow was approximately 10 liters per hour. After ten minutes agitation the air was turned ofi. The volumes of oil and foam, as indicated by the graduation marks on the G-cc. cylinder, were then read. The ratio of oil and foam to o'il sample is as follows:

=ratio of oil and form to oil tics oi' liquid comprising in combination with a measuring receptacle a separate, removable, dished base member adapted substantially to cover the bottom of said receptacle when positioned therein, an internal annular shoulder formed in the peripheral wall of said dished base member,

` a discardable lilter disk of thin, sheet material supported on said shoulder, a ring threaded into said holder for clamping' the disk in position, a pipe for gaseous iuids'v secured to said peripheral wall and communicating with a passageway leading to the enclosed space beneath said filter disk, said pipe being thereby removed from a position centrally of the body of liquid in said measuring receptacle in the path of rising bubbles from said llter disk, to minimize the adherence of bubbles thereto, and'said lter disk being of large diameter or compared to that of the measuring receptacle, whereby bubbles rising through the body of liquid under test are substantially hfomogeneously distributed therethrough.

HERSCHEL G.- SMITH. 

